Safety device for punch-presses.



N. MURPHY.

SAFETY DEVICE FOR PUNCH PRESSES.

. APPLICATION FILED NOV- 5. 1912.

1,295,827. Patented Feb. 25, 1919.

QWTEEJD ATES: rarnnr orrren NELSON MURPHY, or DETROIT, MICHIGAN,ASSIGNOR or oNE-To UnTn ToTHoMAs L.

l BUTTON, or DETROIT, MICHIGAN.

Specification of Letters-Patent.

Patented'Feb. 25, 1919.

Application filed November 5, 1917. Serial No. 200,279.

To 'allwho'm'z't may'conoern:

Be it known that I, NELSON MURPHY, a

citizenof the United States of America, residing at Detroit in thecounty of Wayne and State of "Michigan, have invented certain new anduseful Improvements in Safety Devices for Punch-Presses, of which thefollowing is a specification, reference being had therein totheaccompanying drawings.

This invention relates to a safety device for punch presses, and suchmachines that have predetermined operations when set in motion, theoperations being more or less automatic and to a degree beyond thecontrol of the operator of the machine after the machine hasbeenstarted. 7

The primary. obj ect of my invention is to provide an automaticllockingdevice adapted to predetermine the operation ofa punch press, when thedevice is actuated, said device confining the punch press to a singleoperation, and in this'manner pre'venting a multiplicity of operations,due to carelessness on the part of the operator, breaking; a

part' of; the machinery, or other causes yon'd the control of theoperator, which repeated operations may cause an operators fingers to besevered or the operator otherwise injured.

A further object ofi this invention isto provide a Simple, durable andinexpensive locking device for the driven shaftflof a punch press, sothat said shaftcan only make one revolution and thereby lower and raise,as a single operation, a punch die or other'tool used in the-machinei Myinvention will be hereinafter specifi cally described and then claimed,and reference will now be had to the drawing, wherein- Figure 1 is aside elevation of a punch press provided with a safety device;

Fig. 2 is an enlarged longitudinal sectional view of a portion of themachine, showing the locking device for the main shaft thereof; 1

Fig. 3 is a cross sectional view of the looking device;

Fig. 4 is a vertical sectional view of the trip mechanism, and

Fig. 5 is a horizontal sectional View taken on the line VV of Fig. 4.

In the drawing. there is illustrated, by the way of a suitable machineto which the safety device may be applied, a: punch press- 1 having areciprocable member 2 operated through the medium of a main shaft 3.

This maih'shaft has a'large loose gearwheel' 4 adapted to be driven by asmall gear wheel 5 on a suitahl epower, shaft 6. A conventional form 'ofclutch 7 controls the operation of the main shaft 3 bythe large gearwheel. 4, said clutch being .spring" pressed and having azpin' 8extending into a cam groove 9 in'the periphery of the clutch 7. Amechanisnnincluding a pin rock arm 10, a reach rod 11, and a fulcrumedtreadle 12 ordinarily control the operation of the clutch 7. "Forinstance, and as'shown, the clutch 7 is now out of engagement with thelarge gear wheel 4 and the punch press is inactive." 'When the treadle12 is depressed, the pin 8 is: removed from the groove 9 and the springof the clutch forces the clutch into engagement with the hub portion oftl1e l-arge-gearwvheel 4 and establishes a driving relation between saidlarge gear wheel and the main shaft 3;

groove 9 and after one revolution of'the main shaft 3 theclutch 7 isautomatically withdrawn or restored to normal position.

Sometimes the operator forgets to remove his foot'from the treadle '12and at other times' the clutch mechanism breaks and in either instancethere are repeated operations of the'pr'ess'which are not only liable toinjure the piece'of work lbeing performed clockwise movement or rotationof the main shaft 3. The locking arm 16 has the upper end thereof or anextension 17 thereof connected by a coiled retractile spring 18 to anupright or post 19 carried by the block 14, said spring holding thelocking arm 16 normally in engagement with the main shaft 3, so as tosna into the notch 13 when said notch reaches the end of the locking arm16.

When the treadle 12 isreleased, the pin 8 enters the A suitable casingor housing 20 may inclose that portion of the main shaft 3 in press andthen extends upwardly and is connected to a trip member 24 in a casing25 connected to the side of a punch press. The trip member 24 within thecasing 25 has a spring pressed dog 26 adapted for engagement with adog'27 at the side of a reciprocable member 28 slidable in the casing25. The dog 27 has a side pin 29 extending into an angularly disposedslot 30 in the'side wall of the casing, and one end of the dog ispressed by a spring 31. Both of the dogs are beveled and atpredetermined times are adapted to recede. I

Connected to the lower end of the reciprocable member 28 is a reach rod32 and said rod is pivotally connected to the treadle 12 to be actuatedin synchronism therewith.

In operation and when the treadle 12 is depressed, the member 28 israised and as the dog 27 engages under the dog 26 the trip member 24will be elevated thereby shifting the locking arm 16 so as to releasethe main shaft 3. This operation takes place slightly in advance of theclutch 7 establishing a driving relation between the large gear wheel 4and the main shaft 3, and in consequence of these. successiveoperations, the punch press is placed in operation.

As the dog 27 elevates the dog. 26, the former gradually recedes byvirtue of its pin and slot connection with the casing 25. Eventually thedog 26 is released and by reason of the first operation the dog 27 isnow above the dog 26, and the spring 18 holds the locking arm 16 againstthe rotating main shaft 3 so as to snap into thenotch 13 when said notchreaches the end of the arm 16. This will take place even though theoperator should retain his foot upon the low the dog 27 to assume itsnormal osition 7 beneath the same. 7

It is thought that the operation and utility of the safety device willbe apparent without further description, and while in the drawing thereis illustrated a preferred embodi- .ment of my invention, it is to beunderstood that the structural elements are susceptible to such changesas fall within the scope of the appended claim.

What I claim is The combination with a punch press hav ing a main shaft,and a clutch adapted to automatically control the operation of saidshaft, of a pivoted locking arm engaging in said shaft to hold saidshaft against rotation, a tri member connected to said locking arm,

a reciprocable member confronting said! trip member actuated insynchronism with said clutch, and a' pivoted spring pressed dog carriedby each member with said dogs normally engaging eachother and adapted.to cause said trip me'mber to be elevated by said reciprocable memberto withdraw said arm from within said shaft to release the same, and oneofsaid dogs receding over the other when said reciprocable memberassumes normal position.

In witness whereof I aflix my signature in the presence of twowitnesses.

NELSON MURPHY. Witnesses; V

KARL H. BUTLER, ANNA M. Donn.

Copies of this patent may be obtained for five cents each, by addressingthe "Commissioner of Patents, Washington, D. C.

